The FEBEX Project. General Overview

1997 ◽  
Vol 506 ◽  
Author(s):  
F. Huertas ◽  
J.L. Santiago
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Near Field ◽  
Thermal Response ◽  
Crystalline Rock ◽  
Full Scale ◽  
Deep Geological Disposal ◽  
Heating Test ◽  
Large Scale Tests ◽  
Term Performance

ABSTRACTUnderstanding the near-field evolution of a deep geological disposal system for HLW is crucial for assessing its long term performance and, therefore, safety. For that reason ENRESA devised the FEBEX Project, a Full Scale Engineered Barriers Experiment in crystalline rock. The project consists of a full-scale “in-situ” heating test, a large-scale laboratory mock-up and supporting materials tests, and modelling.Even though the object of the project is to contribute to the search for methods of behaviour and of safety analyses for a repository, other subinvestigations have been/are being included. The stated objectives are to demonstrate the procedures of constructing an engineered barrier system (EBS), especially the fabrication, handling, and installation of bentonite blocks (buffer) at an almost industrial scale, to improve and validate the numerical models for thermo-hydro-mechanical behaviour, and to investigate the geochemical processes that are produced in the buffer including canister corrosion, as well as the generation and transport of gas. Since early 1997, with the commencement of the heating phase, both large-scale tests have been fully operative. At this point it can be said that the demonstration objective of constructing the EBS has been successfully achieved. The measured thermal response of the buffer follows the pattern predicted in the preliminary modelling. The saturation rate of the buffer and associated mechanical processes are being continuously monitored.

Coupled Thermo-Hydro-Geochemical Models of Engineered Barrier Systems: The Febex Project

2000 ◽  
Vol 663 ◽  
Author(s):  
J. Samper ◽  
R. Juncosa ◽  
V. Navarro ◽  
J. Delgado ◽  
L. Montenegro ◽  
...  
Keyword(s):  
Large Scale ◽  
Reference Model ◽  
Numerical Models ◽  
Full Scale ◽  
Small Scale ◽  
Model Parameters ◽  
In Situ Test ◽  
Wide Range ◽  
Engineered Barrier

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

Large Scale Tests of Strain Capacity of Pipe Sections With Circumferential Defects Subjected to Installation-Induced Plastic Strain History

2009 ◽  
Author(s):  
Ba˚rd Nyhus ◽  
Erling O̸stby ◽  
Zhiliang Zhang ◽  
Erlend Olso̸ ◽  
Per Arne Ro̸stadsand ◽  
...  
Keyword(s):  
Large Scale ◽  
Base Material ◽  
Bending Moment ◽  
Full Scale ◽  
Strain History ◽  
Strain Capacity ◽  
Four Point Bending ◽  
Full Scale Tests ◽  
Circumferential Defects ◽  
Large Scale Tests

Installation of offshore pipelines by reeling introduces plastic pre-straining. The pre-strain history is not homogenous and it will vary around the circumference of the pipe. The pre-strain history will modify the yield and flow properties. Also, the fracture toughness may be influenced by the pre-straining. The result is that the bending strain capacity of pipelines during operation will differ depending on how the bending moment coincides with pipe orientation during installation. Three full scale tests of 12″ x-60 pipes with wall thickness 19.3mm and a 3×100 mm outer surface defect were performed to investigate the effect of pre-strain history. Two pipes were pre-strained in bending to 2% strain in the outer fibre and then straightened to simulate the reeling. The final tests to establish the strain capacity during operation as a function of strain history were performed in four point bending with an internal pressure of 325 bar. The strain capacity for the side of the pipe that ends in tension and the side that ends in compression from pre-straining was 1.7% and 2.6% respectively. The strain capacity of the third test without pre-straining was 5.7%. The results show that pre-straining will modify the strain capacity and the effect must be taken into account in engineering critical assessment of pipes during operation. The effect of prestraining should be evaluated for all installation methods that involve plastic deformation during installation, and not only reeling. It is important to note that the notch size in the full scale tests was larger than what would normally be accepted for reeling. In addition the notch was positioned in base material and not in weld metal, which is a more realistic position for a notch. The welds are normally overmatched and this might reduce the effect of prestraining.

scholarly journals A New Method for Seismically Safe Managing of Seismotectonic Deformations in Fault Zones

2020 ◽  
pp. 45-66
Author(s):  
Valery V. Ruzhich ◽  
Evgeny V. Shilko
Keyword(s):  
Large Scale ◽  
Scale Validation ◽  
Fault Zones ◽  
Full Scale ◽  
Coseismic Slip ◽  
Stick Slip ◽  
Slip Regime ◽  
Deep Wells ◽  
Seismic Vibrations ◽  
Large Scale Tests

AbstractThe authors outline the results of long-term interdisciplinary research aimed at identifying the possibility and the methods of controlling tangential displacements in seismically dangerous faults to reduce the seismic risk of potential earthquakes. The studies include full-scale physical and numerical modeling of P-T conditions in the earth’s crust contributing to the initiation of displacement in the stick-slip regime and associated seismic radiation. A cooperation of specialists in physical mesomechanics, seismogeology, geomechanics, and tribology made it possible to combine and generalize data on the mechanisms for the formation of the sources of dangerous earthquakes in the highly stressed segments of faults. We consider the prospect of man-caused actions on the deep horizons of fault zones using powerful shocks or vibrations in combination with injecting aqueous solutions through deep wells to manage the slip mode. We show that such actions contribute to a decrease in the coseismic slip velocity in the fault zone, and, therefore, cause a decrease in the amplitude and energy of seismic vibrations. In conclusion, we substantiate the efficiency of the use of combined impacts on potentially seismically hazardous segments of fault zones identified in the medium-term seismic prognosis. Finally, we discuss the importance of the full-scale validation of the proposed approach to managing the displacement regime in highly-stressed segments of fault zones. Validation should be based on large-scale tests involving advanced technologies for drilling deep multidirectional wells, injection of complex fluids, and localized vibrational or pulse impacts on deep horizons.

Moment-resisting-frames under cyclic loading: Large scale tests and validation of plasticity and damage numerical models

2018 ◽  
Vol 115 ◽  
pp. 564-577 ◽  
Author(s):  
Stella Avgerinou ◽  
Xenofon Lignos ◽  
Pavlos Thanopoulos ◽  
Andreas Spiliopoulos ◽  
Ioannis Vayas
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Numerical Models ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Large Scale Tests

Computational Performance of an Embedded Reinforcement Mesh Generation Method for Large-Scale RC Simulations

2015 ◽  
Vol 12 (03) ◽  
pp. 1550019 ◽  
Author(s):  
George Markou
Keyword(s):  
Mesh Generation ◽  
Large Scale ◽  
Numerical Models ◽  
Research Work ◽  
Full Scale ◽  
Computational Time ◽  
The Third ◽  
Macro Elements ◽  
Computational Performance ◽  
Embedded Mesh

In this paper, a numerical investigation on the limits of an automatic procedure for the generation of embedded steel reinforcement inside hexahedral finite elements (FEs) is presented. In 3D detailed reinforced concrete simulations, mapping the reinforcement grid inside the concrete hexahedral FEs is performed using the end-point coordinates of the rebar reinforcement macro-elements. This procedure is computationally demanding while in cases of large-scale models, the required computational time for the reinforcement mesh generation is excessive. This research work scopes to study and present the limitations of the embedded mesh generation method that was proposed by Markou and Papadrakakis, through the use of a 64-bit operating system. The embedded mesh generation method is integrated with a filtering algorithm in order to allocate and discard relatively short embedded rebar elements that result from the arbitrary positioning of the embedded rebar macro-elements and the nonprismatic geometry of the hexahedral mesh. The computational robustness and efficiency of the integrated embedded mesh generation method are demonstrated through the analysis of three numerical models. The first two numerical models are a full-scale 2-story and a 7-story RC structures while the third model deals with a full-scale RC bridge with a trapezoidal section and a total span of 100 m. Through the third numerical implementation, the computational capacity of the integrated embedded rebar mesh generation method is investigated.

Impacts of changing conditions on far-field radionuclide evolution: background and goals of a newly funded DFG-RFBR project.

2020 ◽  
Author(s):  
Fabien Magri ◽  
Thomas Nagel ◽  
Axel Liebscher ◽  
Victor Malkovsky
Keyword(s):  
Porous Media ◽  
Groundwater Flow ◽  
Open Source ◽  
Large Scale ◽  
Numerical Models ◽  
Basic Research ◽  
Crystalline Rock ◽  
Coupled Processes ◽  
Far Field ◽  
Long Time

<p>To date, the most secure, technically feasible and internationally accepted solution for the safe management of Radioactive Waste (RW) is burial in deep host rock units, also referred to as disposal in a deep geological repository (DGR). For this purpose, it is mandatory to select a site in a hydrogeological setting which provides sufficiently safe natural conditions for waste isolation from groundwater flow over long time periods (up to 1 Ma).</p><p>However, over such a long time period, external factors (e.g. climate change) and intrinsic basin features (e.g. tectonics), here referred to as changing conditions, will impact the hydrological (H), thermal (T), mechanical (M) and chemical (C) state of the entire system. Therefore, it is crucial to better understand the impacts of changing conditions on far-field radionuclide mobilization and behavior in order to select the most suitable DGR for RW disposal.</p><p>Multiphysics simulators offer powerful tools that couple groundwater flow (H), transport of heat (T), as well as geochemical reactions (C) in a deforming solid framework (M). These coupled THM-C numerical models can provide evaluations for performance and safety assessment of a DGR at different scales. However, a limited number of studies so far addressed the far-field evolution of radionuclides under the changing conditions listed above.</p><p>The newly funded German Science Foundation (DFG) and the Russian Foundation for Basic Research (RFBR) project “INFRA” (NA1528/2-1 and MA4450/5-1; 2020-2022) aims to investigate the impacts of (i) glaciation, (ii) permafrost and (iii) tectonic events on the coupled boundaries that control large-scale groundwater flow near hypothetical waste repositories. For this purpose, the open source simulator OpenGeoSys [1,2] will be applied using available data from selected areas of the Yeniseisky Site in Russia [3].</p><p>Though the context of this study is related to RW issues, the outcomes of INFRA will be of interest for any field of geosciences that deals with large-scale simulations of coupled processes under transient boundary conditions.</p><p> </p><p>[1] Kolditz, O., Bauer, S., Bilke, L., Böttcher, N., Delfs, J. O., Fischer, T., … Zehner, B. (2012). OpenGeoSys: an open-source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media. Environmental Earth Sciences, 67(2), 589–599. https://doi.org/10.1007/s12665-012-1546-x</p><p>[2] Bilke, L., Flemisch, B., Kalbacher, T., Kolditz, O., Helmig, R., & Nagel, T. (2019). Development of Open-Source Porous Media Simulators: Principles and Experiences. Transport in Porous Media, 130(1), 337–361. https://doi.org/10.1007/s11242-019-01310-1.</p><p>[3] Laverov, N., Yudintsev, S., Kochkin, B., Malkovsky V. (2016). The Russian Strategy of using Crystalline Rock as a Repository for Nuclear Waste. Elements, 12(4), 253–256. https://doi: 10.2113/gselements.12.4.253  </p>

A proposed wavy shield for suppression of supersonic jet noise utilizing reflections

2021 ◽  
Vol 20 (1-2) ◽  
pp. 4-34
Author(s):  
Reda R Mankbadi ◽  
Saman Salehian
Keyword(s):  
Large Scale ◽  
Flat Surface ◽  
Near Field ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Dominant Frequency ◽  
Wavy Surface ◽  
Initial Region ◽  
Reflected Waves ◽  
Free Jet

In this work we propose replacing the conventional flat-surface airframe that shields the engine by a wavy surface. The basic principle is to design a wavy pattern to reflect the incoming near-field flow and acoustic perturbations into waves of a particular dominant frequency. The reflected waves will then excite the corresponding frequency of the large-scale structure in the initial region of the jet’s shear layer. By designing the frequency of the reflected waves to be the harmonic of the fundamental frequency that corresponds to the radiated peak noise, the two frequency-modes interact nonlinearly. With the appropriate phase difference, the harmonic dampens the fundamental as it extracts energy from it to amplify. The outcome is a reduction in the peak noise. To evaluate this concept, we conducted Detached Eddy Simulations for a rectangular supersonic jet with and without the wavy shield and verified our numerical results with experimental data for a free jet, as well as, for a jet with an adjacent flat surface. Results show that the proposed wavy surface reduces the jet noise as compared to that of the corresponding flat surface by as much as 4 dB.

scholarly journals Vanadium Redox Flow Batteries: A Review Oriented to Fluid-Dynamic Optimization

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 176
Author(s):  
Iñigo Aramendia ◽  
Unai Fernandez-Gamiz ◽  
Adrian Martinez-San-Vicente ◽  
Ekaitz Zulueta ◽  
Jose Manuel Lopez-Guede
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Renewable Energy Sources ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Batteries ◽  
Design Flexibility ◽  
Flow Batteries ◽  
Exchange Membrane ◽  
Vanadium Redox

Large-scale energy storage systems (ESS) are nowadays growing in popularity due to the increase in the energy production by renewable energy sources, which in general have a random intermittent nature. Currently, several redox flow batteries have been presented as an alternative of the classical ESS; the scalability, design flexibility and long life cycle of the vanadium redox flow battery (VRFB) have made it to stand out. In a VRFB cell, which consists of two electrodes and an ion exchange membrane, the electrolyte flows through the electrodes where the electrochemical reactions take place. Computational Fluid Dynamics (CFD) simulations are a very powerful tool to develop feasible numerical models to enhance the performance and lifetime of VRFBs. This review aims to present and discuss the numerical models developed in this field and, particularly, to analyze different types of flow fields and patterns that can be found in the literature. The numerical studies presented in this review are a helpful tool to evaluate several key parameters important to optimize the energy systems based on redox flow technologies.

scholarly journals Process-Based Model Prediction of Coastal Dune Erosion through Parametric Calibration

2021 ◽  
Vol 9 (6) ◽  
pp. 635
Author(s):  
Hyeok Jin ◽  
Kideok Do ◽  
Sungwon Shin ◽  
Daniel Cox
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Model Performance ◽  
Coastal Dunes ◽  
Wave Transformation ◽  
Storm Event ◽  
Face Model ◽  
Dune Erosion ◽  
Simulation Performance ◽  
Sand Bar

Coastal dunes are important morphological features for both ecosystems and coastal hazard mitigation. Because understanding and predicting dune erosion phenomena is very important, various numerical models have been developed to improve the accuracy. In the present study, a process-based model (XBeachX) was tested and calibrated to improve the accuracy of the simulation of dune erosion from a storm event by adjusting the coefficients in the model and comparing it with the large-scale experimental data. The breaker slope coefficient was calibrated to predict cross-shore wave transformation more accurately. To improve the prediction of the dune erosion profile, the coefficients related to skewness and asymmetry were adjusted. Moreover, the bermslope coefficient was calibrated to improve the simulation performance of the bermslope near the dune face. Model performance was assessed based on the model-data comparisons. The calibrated XBeachX successfully predicted wave transformation and dune erosion phenomena. In addition, the results obtained from other two similar experiments on dune erosion with the same calibrated set matched well with the observed wave and profile data. However, the prediction of underwater sand bar evolution remains a challenge.

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